Running a Carter black electric pump. => http://www.summitracing.com/parts/cr...FYxDMgodRUMAxA

Actually toying with going back to a mechanical pump due to better reliability - block has the mounting boss and camshaft has the lobe.

So you were sucking in air at the fitting? I'm going to look for stupid stuff like that, including a cracked fuel pickup.

Budman FWIW we put a 533ci in a friend's baja 250 sport this spring, hit a whopping 60 first time out. It was way lean, threw some fuel at it and hit 69mph gps pretty quick. Listen to Mild, the tune is everything.

How many steps up did you have to go with your jetting?

Quick question - if I was running lean enough to cause me to drop 100+ HP off the table, should I have seen any elevation in engine oil temp? Granted, I probably only ran it WFO for a minute or so.

I'm going to check fuel delivery, timing, etc., and probably try jetting it richer just to see what happens. However, here's what I'm having trouble wrapping my head around: If it is jetted lean now, I would expect that it would have been lean on the dyno too, in which case I would think the A/F numbers would have told us, and it would not have made the power it did. How is it suddenly jetted lean now that it is in the boat? Especially with what should be more restrictive wet exhaust with muffled tips. Not doubting any of the excellent suggestions and advice I have had per se, just trying to understand what's going on.

I agree. Lightnings shouldn't be any different. You just have to make sure you don't put them too close to where the water mixes.

Three years ago I warmed up a couple of HP 500's. They were in the 550hp range running fully dressed and wet exhaust on the dyno. We could not jet the carb fat enough. Ended up with 1000cfm pro systems. My guess is you are way too lean.

When you keep adding jet with no response it's because the emulsion aren't sized properly. That's the nice thing with the new carbs they have jets...

Lightning headers could be scavenging better on top. They make good power.

The fuel psi gauge should tell the story.

Personally, i think that pump setup you have sucks. 18psi pump 100gph pump i see? And you are running a regulator down to 7psi i assume?

I know nothing about those pumps, and cant find the info on what it reallt flows at 7psi. My gut tells me to toss it in the lake though lol

If i were in your shoes, i'd invest in a six valve mechanical pump from baker engineering , or teague sells them. Self regulated , 1/2 NPT ports, will support more than enough power, and simple as can be.